In Europe, at least nine people died this year after being infected with the West Nile virus. Global warming makes it easier for mosquitoes to spread the virus, although virologist Johan Neyts (KU Leuven) emphasizes that only a minority get symptoms.
Paul Notelteirs25 augustus 2023, 03:00
What is West Nile Virus?
“It is a virus of which birds are the natural host and which is spread via mosquitoes. Humans and horses are also hosts, but they don’t really contribute to the spread. The virus was first identified in Uganda and circulated mainly in parts of Africa until the 1950s. In 1999 there was suddenly an outbreak in New York that spread to the rest of the United States and Canada. This spread probably took place via migratory birds. The virus has also been circulating in southern and central Europe for years.
“Eighty percent of those infected never develop symptoms, the others develop West Nile fever after two to fourteen days. They can then get headaches, muscle aches and fever, among other things. In 1 in 150 cases, the virus also affects the brain, resulting in meningitis. For one tenth of those patients with neurological symptoms, the outcome is fatal.”
Six people have already died of West Nile fever this summer in Italy and Hungary. Is the number of cases on the rise?
“The virus is circulating, but I don’t think the number of infections is increasing alarmingly. In Europe, 125 infections were reported this year, with Italy and Greece leading the way. Since only one-fifth of patients develop symptoms, the total would be a good six hundred infections. That may still be an underestimate as some think they just have a fever and thus never go to the doctor. Nine people have already died from West Nile fever this year, according to figures shared by the European Center for Disease Prevention and Control last week. I think that number, with the cases in Italy and Hungary, has now risen to about fifteen.”
Johan Neyts: “Travellers from Central or Southern Europe who suddenly develop a fever or feel ill should seek medical advice.”Image Joris Casaer
What impact does global warming have on the spread of the virus?
“In a warmer and more humid climate, mosquitoes can breed more easily and transmission is faster. This actually applies to all viruses that are spread by mosquitoes. But if you look at the situation in the United States since 1999, you can see that a rapid and explosive outbreak was possible there without the climatic conditions being ideal for the virus. Climate warming may not be such a determining factor for West Nile fever. But you can also not rule out that more problems will arise as it gets warmer in our regions.”
What can holidaymakers do to protect themselves against the virus?
“I think it is always good to protect yourself against mosquito bites. Travelers from Central or Southern Europe who suddenly develop a fever or feel ill should seek medical advice. People who develop neurological symptoms should see a doctor immediately. But all in all, I don’t think people should lie awake if they go on holiday to Italy, say.”
What does West Nile fever treatment look like?
“For mild cases, the typical fever and pain medication will suffice, but there are no antiviral drugs available. What we actually need is an antiviral that works against West Nile virus as well as other flaviviruses such as dengue, Zika and tick-borne encephalitis. There is also no vaccine to prevent infection. Research is being done into this, but those vaccines are far from being rolled out. We already have effective vaccines for some of those flaviviruses: for example, people can be vaccinated against tick-borne encephalitis, the virus that ticks mainly spread in Alpine regions at an altitude of 1,000 meters and in Scandinavia.”
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2023-08-25 01:00:21
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